Assign the execution permissions on the entire site

By assigning the execution permission inside the site, automatically the IIS console protects itself and changes the public folder permissions by removing the necessary Everyone change permissions of such a folder. The consequence of such a procedure is that every application entered in the public folder (forum, guestbook, chat) will not work any more.
In the same way you must never change the special folders in secondary webs: they will lose all the permissions.